Earth is at a critical crossroads. While revolutionary advances in science and technology have lifted humanity to new heights of prosperity and longevity in many parts of the world, hundreds of millions of people are vulnerable to the impacts of hazards and natural disasters, extreme poverty, infectious disease and a host of other challenges. At the same time, human activity, especially in the last 100 years, is threatening the health of the environment and potentially posing risks of unprecedented magnitude to our shared future. Today, approximately one in six people on the planet subsist on less than $1 a day. The world?s population is expected to increase to 9 billion people by 2050, further straining Earth?s resources and humanity?s ability to thrive. With a window of opportunity to head off the most severe impacts of these challenges, The Earth Institute at Columbia University is working to help the world pave a path toward sustainability.